TWI781257B - Material temperature sensor for stencil printer, print head assembly, and method of operating the same - Google Patents

Abstract

A print head assembly of a stencil printer includes a print head frame and a wiper blade assembly coupled to the print head frame. The wiper blade assembly includes wiper blades that contact the stencil to print solder paste onto the stencil during a print stroke. The wiper blades are configured to force solder paste through the apertures of the stencil. The print head assembly further includes a dispensing unit coupled to the print head frame. The dispensing unit is disposed between the wiper blades to deposit solder paste between the wiper blades. The dispensing unit includes a cartridge receiver. The print head assembly further includes a cartridge positioned in the cartridge receiver and a sensor coupled to the print head frame proximate the cartridge. The sensor is configured to measure a temperature of the cartridge.

Description

Material temperature sensor for stencil printer, print head assembly and its operating method Law

The present disclosure relates to apparatus and processes for dispensing materials, and more particularly to apparatus and processes for dispensing solder paste in a screen or stencil printer.

In surface mount circuit board manufacturing operations, a stencil printer may be used to print solder paste onto the circuit board. Typically, a circuit board with a pattern of pads or some other, usually conductive surface onto which the solder paste will be deposited is automatically fed into a stencil printer, and one or more small Holes or marks (called fiducials) to properly align the board with the stencil or screen of the stencil printer before printing solder paste onto the board. In most systems, an optical alignment system is used to align the board to the stencil.

Once the board is properly aligned with the stencil in the printer, the board is raised onto the stencil, the solder paste is dispensed onto the stencil, and the wiper blade (or scraper) is moved across the stencil to force the solder paste through the pores in the stencil and onto the plate. As the squeegee moves across the stencil, the solder paste tends to roll in front of the blade, desirably causing mixing and shearing of the solder paste in order to achieve the desired viscosity for filling. Fills the screen or holes in templates. Solder paste is typically dispensed onto the stencil from standard cartridges, such as those manufactured by SEMCO Corporation.

Known systems to control the temperature of the material heat the material after it leaves the original packaging (eg, cassette). Reference may be made to U.S. Patent No. 6,453,810 which discloses that a PID controller can be used to apply heaters and/or coolers and a feed mechanism (thermocouple or RTD in direct contact with the material) to stabilize the paste within the material deposition chamber temperature. The temperature information is not used by the system for any other reason and is only used within the control loop.

One aspect of the disclosure is a stencil printer for printing a component material on an electronic substrate. In one embodiment, the stencil printer includes: a frame; a stencil coupled to the frame, the stencil having apertures formed in the stencil; a support assembly coupled to the frame, the a support assembly configured to support the electronic substrate in a printing position beneath the stencil; and a print head assembly coupled to the frame in a manner such that the print head assembly is configured to Period traverses the template. The printing head assembly includes: a printing head frame, and a wiping blade assembly, and the wiping blade assembly is coupled to the printing head frame. The wiper blade assembly further includes a wiper blade contacting the stencil to print solder paste onto the stencil during a printing stroke. The wiping blades are configured to force solder paste through the pores of the stencil. The print head assembly further includes a distribution unit coupled to the print head frame. The dispensing unit is arranged between the brush blades to deposit solder paste between the chips. The dispensing unit includes a cartridge receiver. The printhead assembly further includes a cartridge disposed in the cartridge receiver, and a sensor coupled to the printhead frame proximate the cartridge. The sensor is configured to measure a temperature of the cassette.

Embodiments of the stencil printer may further include a non-contact sensor. The non-contact sensor can be an infrared light sensor. The non-contact sensor can be fixed to the print head frame by a bracket. The bracket can be configured to orient the contactless sensor at an angle relative to an orientation of the cassette. The printhead assembly may further include a translation assembly coupled to the frame and the dispensing unit. The translation assembly may be configured to move the dispensing unit during a printing stroke in a direction transverse to the direction of movement of the print head assembly. The print head assembly may further include a sliding mechanism coupled to the frame and the dispensing unit. The sliding mechanism can be configured to move the dispensing unit in a z-axis direction.

Another aspect of the disclosure is a method of printing a component material on an electronic substrate. In one embodiment, the method comprises the steps of: delivering an electronic substrate to a stencil printer; placing the electronic substrate in a printing position; bonding a stencil having apertures to the electronic substrate; using a wiper blade to perform a printing stroke to force solder paste through the apertures of the stencil onto the electronic substrate; depositing solder paste between the wiper blades during the printing stroke; and measuring the components contained in a cassette A temperature of the material.

Embodiments of the method may further include measuring, by a sensor, a temperature of the component material contained within a cassette. The sensing The device can be a non-contact sensor. The non-contact sensor can be an infrared light sensor. The method may further comprise the step of placing the contactless sensor relative to the cassette by a stand.

Another aspect of the disclosure is a print head assembly for a stencil printer. In one embodiment, the print head assembly includes: a print head frame, and a wiper blade assembly coupled to the print head frame. The wiper blade assembly includes a wiper blade that contacts the stencil to print solder paste onto the stencil during a printing stroke, the wiper blades being configured to force solder paste through the pores of the stencil. The printhead assembly further includes a distribution unit coupled to the printhead frame. The distribution unit is disposed between the wiping blades to deposit solder paste between the wiping blades. The dispensing unit includes a cartridge receiver. The printhead assembly further includes a cartridge disposed in the cartridge receiver, and a sensor coupled to the printhead frame proximate the cartridge. The sensor is configured to measure a temperature of the cassette.

Embodiments of the printhead assembly may further include a non-contact sensor. The non-contact sensor can be an infrared light sensor. The non-contact sensor can be fixed to the print head frame by a bracket.

Another aspect of the disclosure is a stencil printer for printing a component material on an electronic substrate. In one embodiment, the stencil printer includes: a frame; a stencil coupled to the frame, the stencil having apertures formed in the stencil; a support assembly coupled to the frame, the a support assembly configured to support the electronic substrate at a printing position below the stencil; and a printhead assembly, the printhead assembly A member is coupled to the frame in a manner such that the print head assembly is configured to traverse the stencil during a printing stroke. The printing head assembly includes: a printing head frame, and a wiping blade assembly, and the wiping blade assembly is coupled to the printing head frame. The wiper blade assembly has a wiper blade contacting the stencil to print solder paste onto the stencil during a printing stroke. The wiping blades are configured to force solder paste through the pores of the stencil. The print head assembly further includes a distribution unit coupled to the print head frame. The distribution unit is disposed between the wiping blades to deposit solder paste between the wiping blades. The dispensing unit includes a cartridge receiver. The print head assembly further includes a sensor coupled to the print head frame. The sensor is configured to measure a temperature of the solder paste deposited by the dispensing unit.

Embodiments of the stencil printer may further include a non-contact sensor. The non-contact sensor can be an infrared light sensor. The contactless sensor can be secured to the printhead frame by a bracket configured to orient the contactless sensor at an angle relative to the deposition of the solder paste.

For purposes of illustration only, and not limitation of generality, the present disclosure is now described in detail with reference to the accompanying figures. The disclosure is not limited in its application to the details of construction and arrangement of parts set forth in the following description or illustrated in the drawings. The principles presented in this disclosure are capable of other embodiments and of being practiced or being practiced in various ways. Again, the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. Any reference herein to an example, embodiment, component, element, or action of a system and method in the singular may also have plural embodiments, and any reference herein to any embodiment, component, element Any reference to the plural of an item or action may also have an embodiment encompassing only the singular. References in singular or plural are not intended to limit the presently disclosed systems or methods, components, acts, or elements thereof. Use of "comprising", "including", "having", "containing", "involving" and variations thereof herein means possessing the items listed thereafter and equivalents thereof as well as additional items. References to "or" may be construed as inclusive such that use of any term described with "or" may indicate any of a single, more than one, and all of said terms. Furthermore, in the event of inconsistencies in the use of terminology between this document and documents incorporated herein by reference, the terminology used in the incorporated reference supplements this document; for irreconcilable inconsistencies, the terminology used in this control.

For purposes of illustration, embodiments of the present disclosure are now described with reference to the use of a stencil printer to print component material (eg, solder paste) onto a circuit board. However, those of ordinary skill in the art will appreciate that embodiments of the present disclosure are not limited to stencil printers for printing solder paste onto circuit boards, but may be used in other applications requiring the dispensing of other adhesive component materials, Such as glue and sealant. For example, equipment can be used to print epoxy for use as underfill for wafer scale packaging. Further, stencil printers according to embodiments of the present disclosure are not limited to those that print component materials on circuit boards, but include those that are used to print other materials on a variety of substrates. Surface machines, such as semiconductor wafers. Again, the terms screen and stencil are used interchangeably herein to describe a device in a printer that defines a pattern to be printed on a substrate. In some embodiments, the stencil printer may comprise a Momentum® or Edison ^™ series stencil printer platform supplied by ITW Electronic Assembly Equipment of Hopkinton, Massachusetts.

It is known in the SMT industry that the temperature of the print material (eg, solder paste) has a direct effect on print release characteristics and overall print quality. Typically, within a material deposition system, there is a mechanism (such as a distribution shaft or pump) to maintain a supply of material and is summoned by the software during a print cycle to deposit this material on the stencil as needed. Alternatively, the material can be applied by hand. When this material supply is first installed in the machine or replenished in the machine, the material temperature is unknown. It is advantageous to measure the temperature of the material before depositing the material onto the stencil.

Embodiments of the present disclosure are non-contact (eg, infrared light) temperature probes configured to measure the temperature of a material supply cassette. The data collected from the sensors is used to determine whether the material supply is heated sufficiently from the refrigerated storage temperature of the material supply to permit proper deposition of the material. The sensing capability helps ensure that the material is within the desired temperature range, as defined by the machine operator or setter, even before it is delivered from the supply cassette onto the stencil.

Referring now to the drawings, and more particularly to FIG. 1 , a stencil printer of an embodiment of the present disclosure is generally indicated at 10 . As shown, the stencil printer 10 includes a frame 12 to support the components of the stencil printer. Components of a stencil printer may include in part a controller 14, a display 16, a stencil 18, and a printhead or printhead assembly, generally indicated at 20, configured to apply solder paste in a manner described in more detail below.

As shown in FIG. 1 and described below, the stencil and printhead assemblies may be suitably coupled or connected to frame 12 . In one embodiment, the print head assembly 20 can be installed on the print head assembly elevated frame 22 , and the print head assembly elevated frame 22 can be mounted on the frame 12 . The printhead assembly overhead 22 enables the printhead assembly 20 to move in the y-axis direction under the control of the controller 14 and applies pressure to the printhead assembly 20 when engaging the stencil 18 . In one embodiment, printhead assembly 20 may be placed on stencil 18 and lowered in the z-axis direction to contact and sealingly engage the stencil.

The stencil printer 10 may also include a conveyor belt system (not shown) having tracks for transporting printed circuit boards (sometimes referred to herein as "printed wiring boards," "substrates," or "electronic substrates") to the stencil. The print location on the printer. Rails herein may sometimes be referred to as "pull feed mechanisms" configured to feed, load, or transport circuit boards into the work area of a stencil printer (which work area may also be referred to herein as a "print nest") and Unload the board from the print nest.

The stencil printer 10 has a support assembly 28 to support a circuit board 29 (shown in phantom) which raises and holds the circuit board so that it is stable during printing operations. In some embodiments, the substrate support assembly 28 may further include a specific substrate support system (eg, a solid support, a plurality of pins, or elastic tools) to be placed under the circuit board when it is in the printing position. A substrate support system may be used in part to support the interior areas of the circuit board to prevent bending or warping of the circuit board during printing operations.

In one embodiment, printhead assembly 20 may be configured to receive solder paste from a source, eg, a dispenser, such as a solder paste cartridge, that provides solder paste to the printhead assembly during printing operations. Other methods of supplying solder paste may be used in place of the cartridge. For example, solder paste can be manually deposited between paddles or from an external source. Additionally, in one embodiment, controller 14 may be configured to use a specific software application to control the stencil printer 10 using a personal computer with a suitable operating system, such as the Microsoft ^Windows® operating system provided by Microsoft Corporation. operate. The controller 14 can be networked with a master controller that is used to control a production line for manufacturing circuit boards.

In one configuration, stencil printer 10 operates as follows. The circuit board 29 is loaded into the stencil printer 10 using the conveyor track. The support assembly 28 lifts up and fixes the circuit board 29 to the printing position. The print head assembly 20 is then lowered in the z-axis direction until the blades of the print head assembly contact the stencil 18 with the desired pressure. The printhead assembly 20 is then moved across the stencil 18 by the printhead assembly overhead 22 in the y-axis direction. The print head assembly 20 deposits solder paste through the apertures in the stencil 18 and onto the circuit board 29 . Once the printhead assembly has fully traversed the stencil 18 across the aperture, the printhead assembly is raised off the stencil and the circuit board 29 is lowered back onto the conveyor track. The circuit board 29 is released and transported from the stencil printer 10 so that a second circuit board can be loaded into the stencil printer. To print on the second circuit board 29, the print head assembly is lowered in the z-axis direction into contact with the stencil and moved across the stencil 18 in the opposite direction to that used for the first circuit board.

With additional reference to FIG. 2 , a vision system 30 may be provided for the purpose of aligning the stencil 18 with the circuit board 29 before printing and inspecting the circuit board after printing. In one embodiment, a vision system 30 may be disposed between the stencil 18 and the support assembly 28 that supports the circuit board thereon. The vision system 30 is coupled to a vision overhead 32 for moving the vision system. In one embodiment, video overhead shelf 32 may be coupled to frame 12 and include beams extending between side rails of frame 12 to provide reciprocal movement of video system 30 over circuit board 29 in the y-axis direction. The image overhead shelf 32 may further include a carriage for mounting the image system 30 and is configured to move along the length of the beam in the x-axis direction. In the technical field of solder paste printing, the construction using the image shelf 32 of the moving image system 30 is well known. The arrangement allows the imaging system 30 to be positioned anywhere below the stencil 18 and above the circuit board 29 to individually capture images of predefined areas of the circuit board or the stencil.

After one or more applications of solder paste to the circuit board, excess solder paste may accumulate on the bottom of the stencil 18, and a stencil wiper assembly, generally indicated at 34, may be moved beneath the stencil to remove the excess solder paste. In other embodiments, the stencil 18 is movable on the stencil wiper assembly.

Referring to FIGS. 3 and 4 , a printhead assembly 20 capable of movement in three orthogonal axes (i.e., x-, y-, and z-axis directions) comprises a printing head assembly 20 coupled to a frame 12 of a stencil printer 10. Head frame, generally indicated as 36. In particular, printhead frame 36 includes a main housing 38 with ends 40, 42 extending laterally from the main housing. The main housing 38 functions as a span to support the components of the printhead assembly 20 . The ends 40 , 42 of the main housing 38 are configured to be slidably secured to a pair of rails 44 , 46 provided on the frame 12 of the stencil printer 10 . The end 40 includes a drive block 48 for threadably receiving a ball screw 50 which is driven (rotated) by a motor 52 . The arrangement is such that the printhead frame 36 is configured to move along the rails 44, 46 of the stencil printer frame 12 by controlling the operation of the motor 52 using the controller 14 configured to control the motion of the printhead assembly 20. operation, including the motor.

Printhead assembly 20 further includes rails 54 secured to main housing 38 of printhead frame 36 . Rail 54 extends along the length of main housing 38 between ends 40 , 42 of printhead frame 36 . The printhead assembly 20 further includes a dispensing unit, generally indicated at 56, mounted on a support bracket 58, which in turn is mounted on a track 54 and configured to move along the length of the track. A drive belt 60 driven by a motor 62 powers movement of the dispensing unit 56 along the track 54 to provide translation of the dispensing unit in a direction transverse to the printing stroke direction. The provision of the track 54 , support bracket 58 , drive belt 60 and motor 62 may also be characteristic of the translation provided to the dispensing unit 56 . The dispensing unit 56 is configured to move up and down in the z-axis direction by a slide mechanism 64 associated with the support bracket 58 by a pneumatic actuator.

Dispensing unit 56 includes a cartridge receptacle 66 configured to receive a cylindrical cartridge 68 designed to contain component material, such as solder paste. Cassette 68 is releasably secured to cassette receiver 66 in a well-known manner. In another aspect of the present disclosure, solder paste may be manually deposited on the stencil 18 . As shown, cassette 68 is coupled by fitting 70 to one end of a pneumatic air hose, and the other end of the hose is coupled to a compressor or suitable source of pressurized air. Dispensing of solder paste from magazine 68 is controlled by controller 14 to dispense solder paste onto stencil 18 . In particular, the solder paste is dispensed via a port or nozzle 72 provided at the lower end of the cartridge receiver 66 . A sensor (not shown) is provided to detect if the cartridge is depleted or substantially depleted of solder paste.

The printhead assembly 20 further includes a wiper blade assembly, shown generally at 74, for forcing solder paste into the pores of the stencil 18 during the printing stroke. As shown, the wiper blade assembly 74 has a wiper blade holder 76 mounted on each side of the main housing 38 of the printhead frame 36, with a wiper blade 78 shown in phantom for clarity. In one embodiment, the wiper blade 78 may be secured to the main housing 38 by a clamp mechanism. Arranged so that one wiper blade 78 is adapted to print solder paste as print head assembly 20 advances in one direction during a printing stroke. After the printing stroke is complete, substrates (eg, circuit boards) are ejected from the stencil printer 10 and subsequent substrates are conveyed to the stencil printer and placed in the stencil printer for printing. Next, another wiper blade (not shown) provided on the other side of main housing 38 forces solder paste into the pores of stencil 18 while print head assembly 20 advances in a reverse direction during another print stroke.

The amount of solder paste dispensed between the wiper blades 78 is controlled by the controller 14 (or in another aspect of the disclosure, by the stencil printer operator). The nozzles 72 of the dispensing unit 56 are arranged between the wiping blades 78, and the dispensing unit is lowered along the z-axis direction by the sliding mechanism 64 and the pneumatic actuator, everywhere in the dispensing area defined by the wiping blades The solder paste is dispensed such that the nozzles of the dispensing unit are arranged between the wiper blades. Translation of the dispensing unit 56 is caused by activating the motor 62 to dispense along the length of the wiper blade 78 .

Referring to FIGS. 5 and 6 , the dispensing unit includes a non-contact sensor 80 mounted on the main housing 38 of the print head frame 36 via a bracket 82 . A non-contact sensor 80 , which may employ an infrared light sensor, is placed to sense the material in the cassette 68 held by the cassette receptacle 66 . Alternatively, a non-contact sensor 80 may be placed to detect dispensed material on the stencil 18 as the material is applied by manually depositing the material on the stencil. This embodiment is described with reference to Figure 7 below. Bracket 82 is configured to guide non-contact sensor 80 toward cassette 68, generally at an angle with respect to the vertical orientation of the cassette. The distance at which the contactless sensor 80 is spaced from the cassette 68 by the bracket 82 depends on the type of contactless sensor selected. For example, the sensor may be spaced from the pocket 68 by a distance of 3 millimeters (mm) to 1000 mm for one type of sensor. In one embodiment, the size of the sensing spot generated by the non-contact sensor 80 corresponds to the distance between the non-contact sensor 80 and the cartridge 68 . Thus, by increasing the separation between the contactless sensor 80 and the pocket 68, the sensing spot size is increased. Accordingly, distances in the range of 3 mm to 300 mm are used in print head assemblies of embodiments of the present disclosure. In one embodiment, a distance of 75 mm is chosen. In one embodiment, the non-contact sensor 80 is secured to the bracket by a threaded body and a cage nut (each indicated at 84 ) secured against both sides of the bracket 82 . Bracket 82 is fabricated from metal, such as aluminum or steel; however, other materials, such as hard plastic, may be used.

The non-contact sensor 80 is configured to detect the temperature of the material in the cassette 68 to confirm that the temperature is correct for a particular application using criteria predetermined by a user setup process in which The operator of the stencil printer 10 inputs settings for the stencil printer before feeding materials from the cassette. The non-contact sensor 80 is connected to the controller 14 and is configured to notify the operator immediately when material is not ready for deposition. Additionally, temperature data may be collected by controller 14 for each material dispensed from cassette 68 . The collected data can be fed back to the stencil printer 10 for additional actions, or can be sent to a data collection system, such as a downstream machine or internal or remote statistical processing.

In certain embodiments, the operator of the stencil printer 10 has a material supply process in which material supply containers or cassettes stored at refrigerated temperatures are removed from the refrigerator prior to use in the stencil printer, ideally with sufficient time to Bring to the proper temperature before installing in the machine. By using the non-contact sensor 80, the operator can configure the stencil printer 10 to identify cassettes before material is deposited onto the stencil 18 or enters the chamber (in the case of a closed (pressurized) print pump). The material in 68 is indeed at the proper temperature.

In some embodiments, the non-contact sensor 80 is an infrared light sensor to detect the temperature of the cartridge 68 . Infrared light sensors are electronic sensors configured to measure infrared light radiated from objects placed in the sensor's field of view. Objects with a temperature above absolute zero emit heat in the form of radiation. In one embodiment, the infrared light sensor is a T-GAGE ^™ M18T series infrared light temperature sensor supplied by Banner Engineering Corporation of Minneapolis, Minnesota. The T-GAGE ^™ sensor is a passive, non-contact, temperature-based sensor used to detect the temperature of an object within a sensing window and output a proportional voltage or current depending on the sensor configuration.

Figure 7 illustrates the use of a non-contact sensor 80 secured to a bracket 82 such that the non-contact sensor is directed to the reticle. In particular, the non-contact sensor 80 is fixed to the bracket 82 to guide the non-contact sensor towards the deposition of the solder paste 86 . As with reference to the embodiment in Figures 5 and 6 above, the non-contact sensing The distance between the sensor 80 and the deposition of solder paste 86 by the holder 82 depends on the type of non-contact sensor selected. As shown, the non-contact sensor 80 is secured to the bracket threaded body and cage nut, secured against both sides of the bracket 82 . The non-contact sensor 80 is configured to detect the deposition temperature of the solder paste 86 to determine the deposition temperature before performing the stencil printing operation. The non-contact sensor 80 is connected to the controller 14 and is configured to notify an operator immediately when a deposit of solder paste 86 is not ready for a stencil printing operation.

Embodiments of a printhead assembly with the above described non-contact sensors are used to monitor the temperature of a supply cartridge of solder paste in a printer, at least in part to ensure that the solder paste reaches the proper temperature prior to initial print deposition. Embodiments of the printhead assembly with the above described non-contact sensors are further used to ensure that the solder paste is heated to the proper temperature for deposition when stored at a temperature below the proper application temperature.

Embodiments of the printhead assembly with the above described non-contact sensors can also be used to measure the temperature of the material to be deposited, as well as the temperature of the substrate (eg, circuit board 29) on which the material is deposited and the solder paste deposited on the template. For example, in the SMT assembly industry, it is well known to preheat the substrate in the dispenser, usually prior to the deposition of the underfill material. Typical applications use what is known as a pre-heated "chuck" (an area or zone for heating the PCB to a predetermined temperature) prior to transport into the dispensing area to receive the material to be dispensed. The problem with the preheating zone is that there is typically only one feedback sensor to measure the temperature of the overall preheating clip, typically 330mm X 250mm. This feedback from a single sensor typically senses the temperature at one location, and the result is assumed to be representative of the temperature for the overall preheat zone, and may not necessarily reflect the true temperature at the specific location of interest, such as the temperature of a critical component. Further, without feedback of the actual temperature of a specific location of the substrate, the time allocated to pre-heat the substrate is usually chosen to ensure that at least enough time has elapsed for the substrate temperature to stabilize. This can mean spending valuable time waiting for an excessively long "enough" time period.

A non-contact sensor (e.g., non-contact sensor 80) placed above the substrate on the pre-heated chuck can be used to confirm that the substrate is indeed at the proper temperature before proceeding with the dispensing operation without waiting longer than necessary to ensure system parts are at precise temperatures. By installing non-contact sensors at specific positions on the substrate, the real temperature at critical positions can be measured. Further, by attaching sensors to a deposition head (or other mechanism, such as a vision probe in a printer) that can move over the substrate in the x- and y-axis directions, it is possible to measure the temperature. The non-contact sensor can also be mounted on a mechanism that moves back and forth from the target of the temperature measurement, or that the target can move relative to the sensor in the x-, y-, and z-axis directions. This configuration allows the effective spot size of the sensor to be adjusted or trimmed to the application's needs. For example, non-contact sensors can be mounted on vertical steps and oriented to look down at the substrate. By moving the lower vertical steps and the sensor closer to the substrate, the temperature of a smaller localized spot can be measured. By moving the vertical steps and the sensor up and thus further away from the substrate, the measured temperature can be effectively averaged over a larger area. This can also be achieved by moving the target to a specific position relative to the sensor and achieve a specific spot size. These arrangements permit sensing of temperature averaged over an area of controllable size, where the size of the sensing area can be optimized for application requirements. Therefore, by installing the sensor to the Z-step, and then installing the Z-step to the X-Y positioning system (such as installing a bracket from the pump), the position and size of the point can be controlled at the same time.

By implementing embodiments of the present disclosure, a deposition system can monitor the temperature of the material to be dispensed by the facility workpiece, as well as the temperature of the critical locations on the substrate to which the material is to be dispensed, ensuring that all participants in the deposition process at the desired temperature. Each of these measured temperatures may be used to confirm that process variables are within predetermined ranges prior to performing a deposition process. In addition (or possibly alternatively), such measurements can be shared or stored for data collection purposes, such as Statistical Process Control (SPC), where the quality or yield of a process can be correlated to the variables measured in the process to Used for processing optimization purposes.

In an embodiment of the present disclosure, the provisions of the non-contact sensor 80 may be applied to dispensers as well as printers. The material supplied in the cartridge for dispensing in the dispenser is typically stored at a temperature even lower than that used for solder paste storage. For example, dispensers are sometimes used to dispense multi-part pre-mixed epoxies (which must be kept frozen at industrial freezer temperatures, sometimes as low as -40 degrees Celsius) to prevent premature curing. For such systems, the need to ensure that the material has reached a temperature suitable for dispensing can be critical.

Having thus described several aspects of at least one embodiment of the present disclosure, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art to which this invention pertains. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of this disclosure. Accordingly, the foregoing and drawings are by way of example only.

10‧‧‧Stencil Printer 12‧‧‧Frame 14‧‧‧Controller 16‧‧‧Display 18‧‧‧Stencil 20‧‧‧Print Head Assembly 22‧‧‧Print Head Assembly Elevator 28‧‧‧ Support assembly 29‧‧‧circuit board 30‧‧‧imaging system 32‧‧‧image elevated frame 34‧‧‧stencil wiper assembly 36‧‧‧print head frame 38‧‧‧main shell 40‧‧‧end 42‧‧ ‧End 44‧‧‧Rail 46‧‧‧Rail 48‧‧‧Drive Block 50‧‧‧Ball Screw 52‧‧‧Motor 54‧‧‧Rail 56‧‧‧Distribution Unit 58‧‧‧Support Bracket 60‧‧‧ Drive belt 62‧‧‧motor 64‧‧‧sliding mechanism 66‧‧‧cassette receiver 68‧‧‧cassette 70‧‧‧accessory 72‧‧‧nozzle 74‧‧‧wiping blade assembly 76‧‧‧wiping blade Holder 78‧‧‧Brush blade 80‧‧‧Non-contact sensor 82‧‧‧Bracket 84‧‧‧Clock nut 86‧‧‧Solder paste

Various aspects of at least one embodiment are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. These drawings are included to provide illustration and a further understanding of the various aspects and embodiments, and are incorporated into and constitute a part of this specification, but are not intended as a definition of limitation of any particular embodiment. The drawings, together with the remainder of the specification, serve to illustrate the principles and operations of the described and claimed aspects and embodiments. In the schema, by similar Numerals are used to represent each identical or nearly identical component that is illustrated in the various drawings. For purposes of clarity, not every component may be labeled in every figure. In the drawings: Figure 1 is a front perspective view of a stencil printer according to some embodiments of the present disclosure; Figure 2 is a top plan view of the stencil printer illustrated in Figure 1 with portions removed Figure 3 is a perspective view of the print head assembly of the stencil printer; Figure 4 is a front view of the print head assembly; Figure 5 is a side view of the material temperature sensor of the print head assembly; 6 is a perspective view of a material temperature sensor; and FIG. 7 is a perspective view of another embodiment incorporating a material temperature sensor.

Domestic deposit information (please note in order of depositor, date, and number) None

Overseas storage information (please note in order of storage country, institution, date, number) None

36:Print head frame

38: Main shell

54: track

56: Allocation unit

58: Support bracket

64: sliding mechanism

66: Cassette receiver

68: box

72: Nozzle

80: Non-contact sensor

82: Bracket

84: lock nut

Claims (19)

A stencil printer for printing a component material on an electronic substrate, the stencil printer comprising: a frame; a stencil coupled to the frame, the stencil having apertures formed in the stencil; a support assembly coupled to the frame, the support assembly configured to support the electronic substrate in a printing position below the stencil; and a print head assembly coupled to the frame in a manner, such that the printhead assembly is configured to traverse the stencil during a printing stroke, the printhead assembly comprising: a printhead frame, a wiper blade assembly coupled to the printhead frame, The wiper blade assembly has wiper blades that contact the stencil to print solder paste onto the stencil during a printing stroke, the wiper blades configured to force solder paste through the pores of the stencil, a dispensing unit, the distribution unit is coupled to the print head frame, the distribution unit is configured to deposit solder paste between the wiper blades, the distribution unit includes a cartridge receiver, a cartridge, the cartridge is placed in the cartridge receiver device, a first sensor placed over the electronic substrate to ensure that the electronic substrate is at an appropriate temperature prior to the printing stroke; and a second sensor coupled to the As the printhead frame approaches the cartridge, the second sensor is configured to measure a temperature of the cartridge. The stencil printer as claimed in claim 1, wherein the second sensor is a non-contact sensor. The stencil printer according to claim 2, wherein the non-contact sensor is an infrared light sensor. The stencil printer as claimed in claim 2, wherein the non-contact sensor is fixed to the print head frame by a bracket. The stencil printer of claim 4, wherein the bracket is configured to orient the non-contact sensor at an angle relative to an orientation of the cassette. The stencil printer of claim 1, wherein the print head assembly further includes a translation assembly coupled to the frame and the dispensing unit, the translation assembly being configured to travel laterally during a printing stroke The dispensing unit is moved in one direction of the moving direction of the printing head assembly. The stencil printer as claimed in claim 6, wherein the print head assembly further comprises a sliding mechanism coupled to the The frame and the dispensing unit, the sliding mechanism is configured to move the dispensing unit in a z-axis direction. A method of printing a component material on an electronic substrate, the method comprising the steps of: delivering the electronic substrate to a stencil printer; placing the electronic substrate at a printing position; bonding a stencil having apertures to the electronic substrate ; using a wiping blade to perform a printing stroke to force solder paste through the apertures of the stencil onto the electronic substrate; depositing solder paste between the wiping blades during the printing stroke; by a a first sensor to measure a temperature of the electronic substrate to ensure that the electronic substrate is at an appropriate temperature prior to the printing stroke; and a second sensor to measure the component contained in a cassette A temperature of the material. The method as claimed in claim 8, wherein the second sensor is a non-contact sensor. The method as claimed in claim 9, wherein the non-contact sensor is an infrared light sensor. The method as claimed in claim 9, further comprising the step of: placing the non-contact sensor with respect to the cassette by a bracket. A printing head assembly of a stencil printer, the printing The head assembly includes: a print head frame; a wiper blade assembly coupled to the print head frame, the wiper blade assembly having a wiper blade contacting a stencil to print welds during a printing stroke paste onto the stencil, the wiping blades are configured to force the solder paste through the pores of the stencil; a dispensing unit coupled to the print head frame, the dispensing unit is configured to wipe on the Solder paste is deposited between the blades, the dispensing unit includes a cartridge receiver; a cartridge, the cartridge is placed in the cartridge receiver; a first sensor, the first sensor is placed on the stencil printer above an electronic substrate to ensure that the electronic substrate is at an appropriate temperature prior to the printing stroke; and a second sensor coupled to the printhead frame close to the cartridge, the second sensor The detector is configured to measure a temperature of the cartridge. The print head assembly as claimed in claim 12, wherein the second sensor is a non-contact sensor. The print head assembly as claimed in claim 13, wherein the non-contact sensor is an infrared light sensor. The print head assembly as claimed in claim 13, wherein the non-contact sensor is fixed to the print head frame by a bracket. A stencil printer for printing a component material on an electronic substrate, the stencil printer comprising: a frame; a stencil coupled to the frame, the stencil having apertures formed in the stencil; a support assembly coupled to the frame, the support assembly configured to support the electronic substrate in a printing position below the stencil; and a print head assembly coupled to the frame in a manner, such that the printhead assembly is configured to traverse the stencil during a printing stroke, the printhead assembly comprising: a printhead frame, a wiper blade assembly coupled to the printhead frame, The wiper blade assembly has wiper blades that contact the stencil to print solder paste onto the stencil during a printing stroke, the wiper blades configured to force solder paste through the pores of the stencil, a dispensing unit, the distribution unit is coupled to the print head frame, the distribution unit is configured to deposit solder paste between the wiper blades, the distribution unit includes a cartridge receiver, a first sensor, the first Sensors are placed above the electronic substrate to ensure that the electronic substrate is in a proper temperature; and a second sensor coupled to the printhead frame, the second sensor configured to measure a temperature of the solder paste deposited by the dispensing unit. The stencil printer as claimed in claim 16, wherein the second sensor is a non-contact sensor. The stencil printer as claimed in claim 17, wherein the non-contact sensor is an infrared light sensor. The stencil printer of claim 17, wherein the non-contact sensor is secured to the printhead frame by a bracket configured to orient the non-contact sensor at an angle relative to the deposition of the solder paste. sensor.

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